This invention relates to the handling of latex paints to maintain uniformity, to better conserve the paint, and to reduce costs in manufacturing, shipping and storing.
Oil base paints have been generally marketed in small sized containers from the manufacturer to the retailer, and from the retailer to the customer in the same containers without affecting the quality of the paint or its uniformity.
When latex paints came on the market it was natural to continue this same general marketing system which was believed to be most desirable from a commercial standpoint. With this system the manufacturer had a ready means of advertising by the use of specially designed labels on each can, and the use of costly throw-away paint cans became well developed.
Now, with greater attention to waste and cost reduction, questions should be raised concerning the desirability of costly throw-away containers versus inexpensive refillable containers.
Within the manufacturing and storage of consumer paints, the greatest labor and machinery expense has been allocated to the filling of paint batches into small containers, and the subsequent packaging into cartons and storage in cans, cases or pallets. If these expenses, along with the labor and extensive shipping expenses of selecting, packaging, marking and delivering in small units, could be eliminated; a significant saving to the consumer could develop.
In addition, the latex paint marketing system referred to has raised certain technical problems which have not been fully answered. For instance, since latex paints consist primarily of inorganic pigments and a resin base with a water solvent, they are susceptible to damage from freezing, stratification and skin formation; all of which are chemical processes that tend to reduce the uniformity and workability of the paint.
Manufacturers have generally attempted to overcome these difficulties in the past by the addition of glycol compositions to reduce damage from freezing, and the addition of stabilizers and viscosity control agents to reduce the tendency to stratify and to form skins. However, these additives tend to dilute the paint, produce side effects and add cost.
The relatively small can sizes normally usable by retail paint consumers can be made sufficiently strong to withstand pressures of thermal expansion with a minimum of air space, thus reducing skin formation and water evaporation.
Any attempt to employ large tanks, tote bins and bulk containers in shipment of paint encounters the necessity for sealing the container with a larger air space therein to provide for thermal expansion and contraction of the paint, raising a problem of evaporation and skin formation. Furthermore, the general size of these bulk handling facilities tends to encourage stratification and non-uniformity of the paint.
The skin formation is not readily assimilated in the paint, and the stratification is difficult to overcome fully by subsequent mixing.
Various mechanical mixing devices have been provided for drums of paint as exemplified in early U.S. Pats. No. 1,521,564, No. 2,146,372, No. 2,469,557 and No. 2,143,511, and the ordinary paint paddle is readily available.
Also, it has been suggested that the tinting portion of the manufacturing process be transferred to the retailer by equipping the retailer with equipment that facilitates the metering of small additions of color to a paint base, as exemplified in the Hexter U.S. Pat. No. 2,068,646 and Hoekstra et al U.S. Pat. No. 4,046,287.